|Nov 19, 2010, 06:06 AM|
Taube #2 (or is it 2.5??)
I'm so confused...
OK the first one, yellow and red, smacked a tree and chain link fence and so I decided to try again. I built Taube #2 and flew it once but no vid and it was out of balance and had some problems, all my fault so I removed, re-designed and replaced the tail, changed the aileron control location and method and and, pretty much, re-did everything else except wing and fuselage. It's been 2 days of work and painting Now it's ready for testing tomorrow.
I just love this bird like pre-WWI plane. The original "Multi-Roll Stealth Fighter" and if you don't know why I say that, it's because it was used as a recon/fighter/bomber and over 1200 feet with it's, translucent, doped Linen covering it was almost impossible to see. Just Google it!
Igo Etrich, You Rock!
Re: Recent misunderstanding.
Hope it's all sorted out and there are no hurt feelings. The people on this thread are some of the best in the hobby and the old-timers are the most helpful kindest folk it's ever been my pleasure to run into. They have been unselfish in sharing their knowledge and advice with me.
I'm no expert and I know I"m very vocal in my devotion to the KFm2, but that's because it's been the one simple airfoil that does what I ask it to and never complains. I'm sure there are applications where it would fail completely but I'm not planning to go there. It's too much fun where I am now.
So just build, fly and have fun and I'll ask the RC gods to be good to you.
|Nov 19, 2010, 10:41 AM|
Joined Oct 2008
Nice, etc.: try to be cool, guys. Misunderstandings abound in this media. The R/C guys and gals are amongst the best of any sport- or hobby-centered group I have found anywhere. The only better bunch of people I can point to are at my church, and their standard of conduct is set a little high for this crowd, wouldn't you say?
Anyway, the work that Bruce has done is second to none anywhere, any time. Even the ol' Dickeroo his own bad sef agrees with that. So if you want vital research detail then look at the Viking60 blog and the threads he has started to cover this stuff. There's also the research sister thread to this one.
However -- and, Bruce, this is no slam, dude -- that work is a little over the head of most of the builders who come to this thread looking for simple and easy to build solutions to problems of stability, lift, wing structure, etc. For that you need to look at the like of Steve's stuff on the Cybernaught blog, what Gene has done, even some of my kaka (if you are desperate).
Hunt through the old posts for specific issues that people have raised and addressed. You'll be surprised how many of your questions have already been beaten to death by numerous participants here. And you better be having a good time, you hear? Otherwise we're gonna come over there and whip you with a Conquest antenna.
|Nov 20, 2010, 09:02 AM|
Thats the problem with typing out stuff, its too easy to put things down so they get misinterpreted..
When we say stuff its not anything personal its mostly meant to be helpfull..
Any criticism is meant to get people back on the right track with their model making..
We all realize we don't know it all, and we all try to help newbees get it right..I have made enough mistakes in my time, and its nice to steer beginners away from pitfalls ..
Old timers Steve? we are age challenged, thats all..I have still got a lot of growing up to do....
Back to your glider wings ...if you want ailerons on it just use the simple KFm2 with a 50% top step. If no ailerons make a KFm3 with steps at 50 and 75%
You plan to use 5mm foam so what I do to add strength on a long wing is to add a CF rod or tube spar into the build..
So for that KFm2 I would use a 1/4 x 3/4" balsa spar at the step location but split this into two lengths with the CF spar sandwiched between the two
For the KFm3 the CF spar can be sandwiched in the middle layer of the three
And no balsa spar
total wing depth depends on the foam thickness, I use 6mm depron so I would get 18mm...3 layers or 2 +the balsa spar
If you work back through many pages you will find that there are target %ages for the chord to depth ratio.. 7-10% depth works well but dont get hung up on it.. thinner wings work ok, but the thicker you go the more drag you get and the wing gets poorer..
So for a 10% and 18mm deep wing the chord would be 180mm 7.2" .... but dont worry a wider chord just lowers the %age and the wing will be fine ....at 7% the chord should be 10.2"....Again these are only rough figures as a guide... so a 7-10" chord would be fine with 18mm depth and Ive flown thin wings where the depth is down to 4% and they are fine.... BUT go too thick at your own peril..
.does any of that make sense....dave
Edit .....some KFm4 constructions added.
Note.. I personally try to avoid CF spars on cost alone, but if you need a thin wing there is no good alternative.
On all depron wings adding the tapes as per my favorite KFm4 build, will add stiffness and strength...and tape make a vast difference, so dont cry if you leave them off and the foam rips on an impact or from flexing..youve been warned...
If you need extra thickness use additional balsa spars for spacers and at the steps.. like my favorite below..
|Nov 20, 2010, 02:25 PM|
Old timers in the "Experience" department. Those of you who have already banged your heads into the walls the rest of us are running towards at full-tilt.
OH! re: growing up... Don't do it. I tried it once and didn't like it at all.
(Texting language for "Back On Topic")
I gave up on Taube #2. Both iterations veered hard left on take off and were not controllable in Yaw. It's a combination of things but, I think, mostly short moment arm, small tail area and small control surfaces. See! Size does count...
Taube #3 is a RET and the airframe is about half done. Tail will be a more conventional size but still the older WWI style. Fuselage is stretched a bit too.
They say: "Third time's a charm." (At least it works out that way with wives.)
Wish me luck.
Edit: 11/22/10 5:37am
Airframe done in 1.5 days. Now it's RET and built light for the BW drive system. KFm2 still with more conventional sizes on the tail surfaces and a 44"span with 400sq in area. I also lengthened the fuselage a bit for a longer moment arm. The proportions on this one look pretty good to me. It's number 3 and I will install gear today, Monday Nov 22, 2010,
Hope it works out...
BTW is anyone besides me having problems with uploaded pictures not displaying??
|Nov 21, 2010, 07:04 PM|
United States, AZ, Green Valley
Joined Jul 2010
Thank you again.
|Nov 22, 2010, 06:34 AM|
Taube Mk3 Maiden...
There are minor thrust and balance issues but overall a decent maiden.
|Nov 22, 2010, 10:38 AM|
USA, ME, Ellsworth
Joined May 2008
"..No I did not try the hand toss test, here in the desert the ground is hard..."
Don't under estimate the value of a test glide or a low powered test glide on a new plane. I always do them on new planes. I like to do it over taller weeds or some other soft landing but a bare spot of lawn or dirt will work too.
Give it a full arm stroke forward push from shoulder level and watch carefully. If it is a little on the nose heavy side (as it should be for a maiden flight) it will go into a gentle descent to the ground and a little elevator will keep it flat as it settles down.
If it dives it is probably too nose heavy, if it swoops up, then stalls, it is probably tail heavy. And tail heavy can be the kiss of death for a maiden flight.
If it lifts the nose, drops a wing, and does a "lawn dart" that is a side effect of the stall. It is called a tip stall and it happens to one side or the other when a wing loses lift.
If it turns a little to either side, you can try a little aileron trim but in most cases a gentle turn is OK as you can deal with it on a powered launch and either trim it out of just deal with it when you can see it better.
Adding a few hundred RPM to the same test glide launch will extend the glide and if you see it is doing OK you can add a little more power, start a climb, and you are off on the maiden. It is a wonderful thing when that happens!
Full power and a hard throw is about the worst way to approach the maiden flight.
Good luck with it!
|Nov 22, 2010, 06:21 PM|
Thanks for the good words...
Now to tweak it and add the iron crosses. If I need weight to balance it and bring the CG forward I'll go with the BP21. That will add almost an ounce to the nose and give me a lot more pulling power. Should fly at 1/3 throttle on cruise with that motor. I'm thinking, make it a one holer and put in the cockpit to carry the microcam???? Hmmmmm, the possibilities are endless.
|Nov 23, 2010, 01:38 AM|
Steve, Taube looks great! Now I imagine it with short, birdie-like Vtail elevator only, and elevons on wings...
Keithflyer - I usually hand-toss from knee level . First slowly, to check CG, then pretty fast to see trim / roll axis balance.
I like the looks of iron cross (those german war medals look great), but for all that nazi thing, I resist to draw them on my planes. (eh, whata heck do my scratchbuilts have in common with war?). Here, you can get into trouble with law if promoting those symbols (I think model airplanes EXcluding, but anyway...), or trading war souvenirs.
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